WO 02/50051 discloses the compound 1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N-{(R)-1′-phenyl-1′-[N′-(carboxymethyl)carbamoyl]methyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,5-benzothiazepine (elobixibat; IUPAC name: N-{(2R)-2-[({[3,3-dibutyl-7-(methylthio)-1,1-dioxido-5-phenyl-2,3,4,5-tetrahydro-1,5-benzothiazepin-8-yl]oxy}acetyl)amino]-2-phenylethanolyl}glycine). This compound is an ileal bile acid transporter (IBAT) inhibitor, which can be used in the treatment or prevention of diseases such as dyslipidemia, constipation, diabetes and liver diseases. According to the experimental section of WO 02/50051, the last synthetic step in the preparation of elobixibat consists of the hydrolysis of a tert-butoxyl ester under acidic conditions. The crude compound was obtained by evaporation of the reaction mixture under reduced pressure and purification of the residue by preparative HPLC using acetonitrile/ammonium acetate buffer (50:50) as eluent (Example 43). After freeze drying the product, no crystalline material was identified.
It would be desirable to discover forms of elobixibat that are sufficiently robust to be suitable for formulation as a pharmaceutical.
Various crystal modifications may have disadvantages including residual solvents, a variable degree of crystallinity and difficulties in handling and formulating. Thus, there is a need for crystal modifications of elobixibat having improved properties with respect to stability, bulk handling and solubility. It is therefore an object of the present invention to provide a stable crystal modification of elobixibat with good crystallinity and other formulation properties.